I've got to say I love picking out a good stamp. When It is time for a new sheet, I enjoy flipping through the binder of options at the post office to find the perfect one that might end up on a plain white envelope headed to a future trade partner.
As I was recently flipping through, I chose a sheet of Yogi Berra stamps. Berra is the first baseball player featured on a stamp since I believe 2012 when Joe DiMaggio, Larry Doby, Willie Stargell and Ted Williams were all featured in an All-Star game set of stamps.
Here's a great article from Baseball Life that highlight many, if not all, of the baseball figures and stadiums honored by the U.S. Postal Service over the years.